Compounded lubricant



Patented Apr. 11, 1944 UNIT 2,346,156 COMPOUNDED LUBRICANT. Bruce B. Farrington, Victor M. Kostainsek, and

George H. Denison,

Jr., Berkeley, Calif., assignors to Standard Oil Company of California, San Francisco, Calif., a corporation of Delaware No Drawing. Application February 16, 1942, Serial No. 431,116

19 Claims.

tering these conditions is, increasingly difficult for three principal reasons.

The first reason is that the newer bearing metals are, in general, more susceptible to the destructive agents of a corrosive nature even though these metals are harder and capable of carrying higher loads than were the conventional Babbitt bearings. Typical of these corrosionsusceptible newer bearings are those composed of cadmium-silver or copper-lead alloys supported upon a steel back. Others of these relatively' new bearing metals are cadmium-nickel alloys and the so-called high lead bearings.

The second reason for increasing dificulty in preventing corrosion is that the changes in engine design have required concurrent marked advances in methods of refining lubricating oils to yield products having high viscosity index or other desired properties. This demand for oils having lesser change in viscosity with changes in temperature, 1. e. higher viscosity index, has

' been met by refining lubricants by certain selective solvent refining or selective solvent extraction processes wherein the lower viscosity index hydrocarbons are selectively dissolved. The selective solvent refining processes are operated to concentrate in one fraction, usually the undissolved lubricant fraction, those compounds of a paraffinic nature which show a smaller change in viscosity upon change in temperature. Selective solvent extraction processes have been found in many cases to yield an oil which, al though satisfactory from the standpoint of viscosity index, is over-refined as respects stability at higher temperatures. This is particularly true where the selective solvent refinement is carried to a point which yields high Viscosity index produdts.

By over-refined oils it'is intended to designate those oils from which naturally-occurring inhibitors normally present in the oil have been removed at least to an extent which materially reduces the stability of the 011 against deterioration at higher temperatures .or which substantially increases corrosiveness of the oil on modern bearing metals. Over-refined oils are not neces sarily high viscosity index oils since oils of intermediate viscosity index are sometimes produced from quite low viscosity index stocks by a. severe refinement which causes a substantial reduction in the natural inhibitor content of the'oil and thereby produces an oil having a correspondingly reduced stability. From the above it should-be apparent that over-refined oils are not limited to those produced by solvent extraction. Other refining processes, e. g. sulfuric acid treatment to produce white oils, remove naturally-occurring inhibitors originally in the oil' when thetreatment is sufliciently severe and thereby produce over-refinement with the attendant difllculties herein discussed.

In general, over-refined oils may be characterized as having natural inhibitors removed to the point where the corrosiveness of the oil is greater than about 40 mgs. on a 1" x 2" coarse-grained copper-lead bearing in a 72-hour corrosion test (subsequently described in more detail) run under the following conditions:

Air rate 30 liters per hour Temperature 300 F.

Catalyst 10 gms. of steel wool and a 6" x 1" copper strip In the appended claims the foregoing 40 mgs. loss in the 72-hour corrosion test is designated as a corrosion index of 40.

The solvent refined oils referred to above, and especially the over-refined oils, are not the only type of oils which become definitely corrosive to the newer bearing metals under normal but severe conditionsof use in internal combustion engines. It has been found that a corresponding adverse reaction, namely, corrosion of alloy bearing metals such as cadmium-silver alloys, also occurs in parafiinic base oils which have not been solvent refined or over refined. These corrosion difiiculties sometimes cause hearing failure after only a few thousand miles of operation. The higher the viscosity index of the lubricating oil the more pronounced in general is the tendency to corrosion of the kind referred to above. Generally speaking, the problem is encountered in oils having viscosity iniexes of '75 and higher, and becomes of major magnitude in oils having a viscosity index of 80 to 85 or higher.

Thirdly, the newer engines require that the crankcase lubricants operate under significantly higher temperatures than heretofore required. It is found that lubricating oils, which are satisfactory and non-corrosive on newer alloy bearings at lower temperatures heretofore normally encountered, become unduly corrosive to these same bearings at the higher temperatures. These higher temperatures approach the borderline of stability of organic compounds and relatively small increases in temperature therefore magnify many-fold the difficulties of inhibiting corrosion and other deterioration such as formation of varnish, carbon, or sludge.

This invention provides a corrosion inhibitor capable of reducing to a very low level, even at temperatures of 325 F. or above, the corrosive tendencies of hydrocarbon oils which become corrosive during use (though initially non-corrosive), such as highly parafiinic and/or overrefined hydrocarbon lubricating oils.

Problems in lubrication of internal combustion engines have been further multiplied by the necessity for addition of stabilizers capable of inhibiting the deterioration of the lubricating oil at elevated temperatures. As engine conditions became more severe, piston ring sticking, varnish" formation on pistons and cylinder walls, and deposition of hard carbon on the piston wall above the top piston ring, have caused trouble in engine operation. These particular difllculties are met by incorporation of stabilizing agents such as aryl metal oxides (metal phenates), salts of aryl carboxylic acids, salts of polycarboxylic acids which preferably have been partially esterified, salts of alkyl carboxylic acids containing a polar group (e. g. mercapto, thioketo, thioether, amino, cyano, phosphino, oxyketo, and hydroxy groups, and the like) near a carboxyl group of the acid, and metal alcoholates. These types of stabilizer are relatively noncorrosive and some have a corrosion inhibiting action under less severe lubricating conditions.

In naphthenic base lubricating oils, or even in oils of intermediate refinement and intermediate viscosity index (e. g. a viscosity index of less than 75) which are not over-refined, various corrosion inhibitors are highly effective under severe service. However, when an over-refined or high viscosity index oil (e. g. of 80 viscosity index or more) is used as a base stock and when the oil is to do service under extreme conditions on corrosion-sensitive alloy bearings, the dimculties presented have seemed almost insurmountable. Thus there was presented a combination of circumstances not previously encountered, namely: (a) the necessity for lubricating corrosion-sensitive hard alloy bearings, (b) the desirability of using a base oil stock inherently more corrosive to such bearings than lower viscosity index or less highly refined oils, and (c) more severe operating conditions, as respects temperature and speed, than the lubricating engineer had previously been requested to meet.

Under this new combination of circumstances it was found that the above-mentioned noncorrosive stabilizers against deterioration at elevated temperatures catalyzed corrosion by the oil although these compounds remained noncorrosive in themselves. Also, it was discovered that various corrosion inhibitors found to be effective to prevent corrosion even by the overrefined or higher viscosity index stocks in the absence of the stabilizers were not effective as anti-catalysts tovdestroy the catalytic corrosion of the stabilizers in such oils. In other words, the anti-catalytic action of an inhibitor in uncompounded hydrocarbon oils formed no adequate basis for predicting that the same inhibitor would selectively poison the stabilizing agent of compounded oils and destroy the agent's catalysis of corrosion without also destroying its catalytic stabilizing action against deterioration at elevated temperatures.

A feature of this invention comprises the provision of a lubricating oil containing a new combination of additives. This new combination of additives is highly effective, both as respects stabilization against deposition of adhesive or resinous materials at elevated temperatures and prevention of corrosion of alloy bearings, when incorporated in over-refined lubricating oils and oils having a viscosity index higher than '75, e. g. a viscosity index of to or higher. Since the new combination of additives is effective even in hydrocarbon lubricating oils which are relatively non-responsive to corrosion inhibitors and stabilizers, the combinations disclosed in more detail hereinafter are exceedingly powerful additives for more responsive oils, such as naphthenic or mixed base lubricants containing naturallyoccurring inhibitors in normal quantities or in oils having a viscosity index of less than 80.

The corrosion inhibitors of this invention comprise long carbon chain multi-bridged thioalkyl compounds having carbon-to-carbon chains of twenty or more carbon atoms in length, and the preferred type is termed herein parafiin wax polythio-dimers."

The term dimer as used herein designates a type of product such as produced by linking together two molecules of hydrocarbon structure by a condensation reaction. Such a reaction is illustrated by condensation of a chlorinated hydrocarbon with an inorganic sulfide whereby a chlorine atom from each of two molecules is displaced and a divalent sulfur atom takes up the free valence of each molecule to thereby connect the molecule together, thus:

The carbon chains so condensed need not be identical or of the same number of carbon atoms to fall within the meaning of the term dimer" as used herein. Similarly, the term "trimer is used to designate compounds in which three molecules are connected by such a condensation reaction, and the term "thiomer is generic to dimers and trimers in which sulfur is the bridging link. Thiomers of a liquid consistency, even though very viscous at ordinary atmospheric temperatures, are preferred and mixtures which are predominantly dimers or trimers yield the best results. The term "multi-bridged as applied to these compounds requires that there be more than one sulfur bridge between at least one pair of the condensing molecules.

The term parafiln wax polythio-dimer designates a condensation product of two molecules of hydrocarbon structure in which at least two sulfur atoms independently connect alkyl carbon chains containing at least twenty carbon atoms. Such a dimer is produced by a condensation of two polyhalogenated alkyl molecules containing at least twenty carbon atoms and in which at least two halogen atoms are split out from each alkyl molecule and at least two sulfur atoms replace the-tree valences of the two molecules.

Modifications within the scope of the invention in its broader aspects include multi-bridged thio compounds in which the terminal valences of the sulfur bridges are separated by two or more intervening carbon atoms of the chain. At least one long carbon chain should be present in the compounds. By long carbon chain it is intended to designate a carbon chain having twenty or more carbon atoms. Relatively straight chains are preferred, although branching in the chain is not precluded; for example, butene and isobutene polymers yield long carbon chains having some branches but are suitable for the p p s of this invention. Paraffin wax is an illustration of a composition containing long carbon chains 01' outstanding value for synthesis of the corrosion inhibitors herein disclosed. 7

The corrosion inhibiting thiomers of this invention may contain organic or inorganic substituents in one or more of the carbon chains. Examples of such substituents are the halogens, chlorine, bromine and iodine, ester groups, 11ydroxyl groups, and metal carboxylate groups.

The corrosion inhibitors of this invention may be prepared by various methods. The following are equations for exemplary reactions:

(1) Reaction of halogenated long chain hydro- 3 carbons and an inorganic sulfide in the presence of added sulfur:

(2) Preparation of a mercaptide and reaction with a halogenated hydrocarbon, one or monothio ethers, dithio ethers, and probably a small proportion of trithio ethers. This particular reaction product is one of applicants preferred species. The reaction product is herein designated parafiln wax thiomers and comprises the product of the reaction of 'a halogenated parafiin wax (preferably containing from about 15 to about 25% chlorine) and an inorganic sulfide such as sodium sulfide or polysulfide.

In order to illustrate the invention and facilitate the practice thereof by those skilled in the art, the following examples of methods of preparing wax thiomers are given:

PREPARATION OF CHLORINATED WAX Crude white scale wax is melted and heated to about 150 to 200 F. and chlorine gas is passed through the melt. The temperature is preferably kept between these limits by adjusting the rates of heating and inflow of chlorine. The density of the mix increases rapidly as the chlorination proceeds and the gravit of the reaction product is thus a measure of the degree of chlorination. When th chlorine content of the wax has reached a desirable percentage the flow of chlorine gas is cut oif and the mixture is blown with either nitrogen or air until substantially free of either chlorine gas or hydrogen chloride. The chlorinated wax is a straw-colored liquid which slowly darkens on standing. Exemplary inspections of such chlorinated waxes are as follows:

Gravit A. P.

PREPARATION OF WAX THIOMERS EXAMPLE 1 The proportions of the reactants are given in the table below:

Reactants Grams Gram moles Chlorinated wax (27.5% chlorine) 8, 520 19 Sodium sulfide (60-62% Nels) 3,760 29. 5 ur 693 21.7 111001101 1 19,000 414 Water s, 185 11s The sodium sulfide utilized was approximately a trihydrate and the amount of water added was just suillcient to produce Na2S.9H2O.

In preparing the wax thiomers the chlorinated wax and alcohol are first thoroughly mixed in a vessel equipped with a stirrer and a reflux condenser. The sodium sulfide is dissolved in the heated water. The sulfur is added and the mixture boiled and stirred until the sulfur dissolves in the aqueous solution. This aqueous solution is added to the alcoholic solution of the chlorinated wax and the whole is refluxed at 185 F. (atmospheric pressure) for twenty hours. The reaction product is then washed with water until free of alcohol and inorganic salts and then dried by airblowing it at elevated temperature. After drying, the final product is filtered.

In a preferred embodiment of the invention the reaction is carried out under conditions such that substantially all the chlorine in the chlorinated wax is removed. In order to facilitate production of this type of product it is preferred that the chlorinated wax contain only about 16% chlorine.

The following table gives analytical results on the various batches of paraffin wax thiomers prepared with some variations in the method of operation:

Via. at Percent Molecular Meflmd 100 s weight l 740 ll. 1 500 l, 711 ll. 8 650 l, 680 ll. 4 753 l, 867 ll. 5 703 l, 922 ll. 6 746 Method 1-Both alcohol and water are used as in the description given above. M ed 2-0nly alcohol is used as a solvent, and the sodium sulfide and sulfur are added directly to the chlorinated wax in alcohol. Method 3- Half the quantity of alcohol and water are used.

EXAMPLE 2 To insure a wax thiomer substantially free of chlorine the following process was utilized:

Chlorinated wax in this example contained 16% chlorine and anhydrous sodium sulfide was used. No water was added and the alcohol was anhydrous. The proportions were as follows:

Reactants Grams Gram moles Chlorinated wax (16% chlorine) 800 1. 9 Sodium metal 100 4. Alcohol (100%) 1,600 35 Sulfur 2. 16

/ The sodium was dissolved in 800 grams of alcohol and half of the resulting sodium ethylate solution saturated with hydrogen sulfide to yield anhydrous sodium hydrosulfide. To this solution the other half of the sodium ethylate was added. The chlorinated wax was dissolved in 800 grams of alcohol and heated to 160 F. The alcoholic reaction product of sodium ethylate and sodium hydrogen sulfide (anhydrous sodium sulfide) was added and the sulfur stirred in. The whole mixture was refluxed for nineteen hours, washed, dissolved in ethyl ether and dried with anhydrous sodium sulfate. After filtering, the ether was evaporated off. v

Yield grams '701 Viscosity at F 1224 Percent S 12.6 Percent C1 1.8

EXAMPLE 3 +2NaCl Clwax-Ol+2NaSH (alcoholic) wax The wax mercaptan is then converted to alkali metal mercaptides by reaction with caustic soda or sodium ethylate as follows:

2 Wax +2Na0 H Wax S H 8 Na The wax mercaptide is then reacted with additional chlorinated wax (15 to 25% chlorine) in alcoholic solution to give a wax multi-bridged sulfide SNa Wax +Cl-wax-Cl lliVax+2NaCh SNa S A typical product of this method had a molecular weight of 8'73, a sulfur content of 6.8%, and a chlorine content of 2.2%.

The proportions of the corrosion inhibitors disclosed herein may vary from about 0.1% to about 2% by weight based on the oil. In the less corrosive and more stable oils 0.25% is sufilcient, while in more corrosive and less stable oils 1% or more may be necessary. The lighter grades of lubricating oils require somewhat more compounding. In an oil such as a solvent refined S. A. E. 30 lubricant from Kettleman Fields, California crude, 0.25% of the corrosion'inhibitor has been found suflicient even in bilizers such as metal phenates.

In general, it has been found that the corrosion inhibitors of this invention are outstanding and not the mere equivalent of the various other sulfides. For example, the same corrosion inhibiting action in over-refined or high viscosity index lubricating oils is not obtainable with ordinary thioethers or disulfides of the type formulaerespectively. The multi-bridged sulfur structures give a corrosion inhibiting action, particularly in over-refined oils or oils having a viscosity index greater than 75, under conditions where various other thioethers and disulfides of the conventional structure are not fully satisfactory. For example, an S. A. E. 10 lubricating oil from a certain Colombian crude is a particularly difllthe presence of other sta- 4 R-S-Ri' is not equivalent to paraffin thiomers as shown In test 1 the temperature was 325 F. as indicated. Ten liters of air per hour were bubbled through the test oil and a copper catalyst was utilized.

In test 2 the temperature was 300 F. as indiby the following data: cated. 30 liters of air per hour were bubbled Test 3 bearing oorr. Test 2 300 I F il strip iiisi EtQ I rosion t estr test in wt loss per on i mg wt loss mil connecting fine grained ga rod b1 72 Cu-Pb 72 mm h s I 6e hrs. are hrs.

, Colombian S. A. E. l0+0.5% sulfurized metal phonatc+0.25% metal organo-phosphate+l.0% cetyl ethyl sulfide 26. 0 65 1 204 Colombian S. A. E. 10+0.5% sull'urized metal phenate+0.25% metal organo-phosphate+l.5% oetyl ethyl sulfide l2. 2 88. 2 40 1 150 Colombian S. A. E. l0+0.5% suliurizcd metal phenate+0.25% metal organo-phosphate+1% parafiin wax thiomer 8. 6 24. 9 9. 6 31 is not the equivalent of a paraflin was thiomer having substantially the same sulfur content. This is illustrated by the following data:

Test 2, 300 F., strip corrosion test mg. wt. loss, coarse grained Cu-Pb, 72 hours Oil Colombian S. A.. E. 10+0.5% sulfurized metal phenate+0.25% metal organo-phosphate+l.0% paraffin wax thiomer (11.8% sulfur I Colombian S. A. E. l0+0.5% sulfurized metal phenate+0.25% metal orgeno ghos hate+l.0% disulfide (R-S-S-Ri) (12.3 a S ur) From these data it is evident that the paraffin wax thiomer is from four to eight times as efiective as oetyl ethyl sulfide, and over three times as effective as a conventional dialkyl disulfide structure with about the same sulfur content in the inhibiting agent. The limit established by the Caterpillar Tractor Company in the high speed Diesel engine corrosion test is 50 mg. in 246 hours for oils of exceptional quality. The above data show that paraffin wax thiomers are capable of producing an oil meeting the test for exceptional quality, whereas the other sulfides, although highly effective as corrosion inhibiting agents, do not yield an oil of exceptional quality with Colombian base stocks. As stated above, it should be borne in mind that this Colombian base stock is very difllcult to handle from the corrosion standpoint, and this particular type of oil was selected for the above tests in order to emphasize the exceptional properties of the corrosion inhibiting agents herein disclosed.

The strip corrosion data above given were obtained in corrosion tests carried out in the following manner: Glass tubes two inches in diameter and twenty inches long were immersed in an oil bath, the temperature of which was automatically controlled to within i1 F. of the test temperature indicated. Approximately 300 cc. of oil under test was placed in each tube and air. was bubbled through it. Strips of the different types of the bearing metals were placed in the oil. The weight loss of each strip was recorded. Before weighing, each strip was washed in petroleum ether and carefully wiped with a soft cotton cloth. The duration of the test was 72 hours. The loss in weight in milligrams in the foregoing corrosion test is termed the corrosion index of the oil.

through the test oil and both a copper strip and 10 grams of steel wool were placed in the oil as catalysts. The bearing metal subjected to corrosion in test 2 was a strip of coarse grained copper-lead bearing. This second type test is the one designated previously for characterizing over refined oils. I

Test 3 is carried out in a high speed Diesel engine by operation under the following conditions:

R. P. M 1400 Brake horsepower 32 Jacket temperature F 200 Oil sump temperature do 210 Air to radiator do.... 125 Oil change hours 60 The corrosion inhibitors of this invention need not be single pure compounds. As a. practical matter, the thiomers are usually mixtures of different compounds. When all of the carbon chains in the thiomers are long the mixtures contain dimers predominantly with smaller proportions of higher homologues such as trimers or even tetramers. As the number of long chain molecules in the thiomers is increased, viscosity also increases and oil solubility decreases until a point is reached where normally solid substantially oil-insoluble products are obtained. It is possible to obtain oil dispersions of the solid products but a liquid viscous readily oil-soluble thiomer is preferred.

Reference has been made in the foregoing specification to the effectiveness of the inhibitors of this invention for selectively poisoning certain stabilizers to minimize the catalytic action thereof on corrosion without destroying the desired catalytic action of such additives in stabilizing the lubricating oil against deterioration at elevated temperatures. Types of stabilizing agents previously mentioned are aryl metal oxides (metal phenates), salts of aryl carboxylic acids, salts of polycarboxylic acids which preferably have been partially esterified, salts of alkyl carboxylic acids containing a polar group near a carboxyl group of the acid, and metal alcoholates.

Incorporation of the multi-bridged thioalkyl compounds heretofore disclosed in hydrocarbon oils having a viscosity index greater than or over-refined oils enhances the responsiveness of these oils to the immediately foregoing types of stabilizers. Thus the multi-bridged thioalkyl compounds act as sensitizers in high viscosity index or over-refined hydrocarbon oils for stabilizing agents of the anti-piston-ring-stlcking type. The corrosion inhibitors herein disclosed are accordingly multi-functional and are therefore both a sensitizer and an inhibitor of corrosion.

The corrosion inhibitors hereinbefore disclosed. cooperate with aryl metal oxides to give a superior oil. Examples of aryl metal oxides are polyvalent metal salts of phenols of the type formula-- in which u, v, w, z and y are selected from the group consisting of hydrogen or radicals of hydrocarbon structure. The phenol preferably contains at least one alkyl group having more than four carbon atoms. The term radicals of hydrocarbon structure" is intended to include alkyl, aryl, aralkyl, alkaryl or cyclic nonbenzenoid groups which may or may not contain inorganic constituents. Likewise, this term includes radicals which contain hydroxyl groups, ether, thioether, keto, thioketo or carboxyl groups.

The aryl metal oxides also may be metal salts of polynuclear phenols, e. g. salts of polyamyl naphtholates.

Examples of specific aryl metal oxides are alkaline earthmetal salts of phenols containing a decyl, dodecyl, tetradecyl, cetyl, octadecyl, eicosyl or wax substituent; aluminum salts of phenols containing a decyl, dodecyl, tetradecyl, cetyl, octadecyl, elcosyl or wax substituent; magnesium salts of phenols containing a decyl, dodecyl, tetradecyl, cetyl, octadecyl, eicosyl or wax substituent; and similar salts of alkyl substituted polyhydroxy phenols. Other metals, e. g. tin, zinc, cadmium, chromium, iron, cobalt and nickel, may be substituted for the foregoing metals.

Tlfese compounds may be prepared by methods disclosed in the art.

The following data exemplify the effectiveness of the corrosion inhibitors herein disclosed in reducing the corrosivity of lubricants containing aryl metal oxides:

300 F. con. test-mg. wt. 10s? coarse grained copperba 7 Oil 24 hrs. 48 hrs. 72 hrs.

Colombian B. A. E. 10 77).... 24. 7 65. 8 105. 8 Colombian S. A. E. 10 (VI=77)+ 0.5% calcium cetyl phanete 12B. 1 160. 2 191. 4 Colombian S. A. E. 10 (V1 2'7)+ 0.5% calcium cetyl phenate+1% parafiin Wax thiomer 8. 25. i 33.

fur and metal phenate is desirably carried out in an organic solution For example, the metal phenate may be dissolved in a small amount of a hydrocarbon oil to form a concentrated solution of 50% by weight or more of the phenate in the oil. The preferred proportion of sulfur is then added to this solution, the reacting ingredients stirred and heated at 300 to 320 F. for about one hour, or until substantially complete reaction is obtained as indicated by the fact that a copper strip will show only a reddish-purple coloring after five minutes submersion in the re action mixture at 300 F.

Examples of aryl metal oxides which may be sulfurized are calcium, barium, strontium, magnesium, zinc, cadmium, aluminum, tin, chromium, iron, cobalt and nickel aryl metal oxides.

The corrosion inhibitors of this invention'also cooperate with aryl metal oxides containing aryl sulfide substituents to yield a superior oil. Examples of such aryl metal oxides are illustrated by the following type formulae;

where R and R1 are radicals of hydrocarbon structure, and M is a metal, preferably a polyvalent metal such as calcium, barium, strontium, magnesium, aluminum, zinc, tin and chromium.

The effectiveness of the corrosion inhibitors of this invention in combination with the above type sulfide substituted aryl metal oxides is shown by the following data:

325 F., strip corr. testing. wt. loss Oil 24 hrs. 48 1111. 72 hrs.

Solvent refined oil base 8. A. E. 30 (VI- 86)+0.75% metal phenate disulflde 17. 2 27. 3 32. l Solvent refined oil base B. A. E. 30 (VI- 86) +0.76% metal phenate disulflde+1% paraffin wax thiomor l. 5 3. 7 6. 4 Standard Diol HD (VI 37) 29. 3 89.4 112. 2 StandardDiolHD (VI=I)+1% paraflin was thlorner 12. 3 15. l 16. 1

An oil solution of a metal phenate containing an aryl sulfide group and of the type listed in the foregoing table may be obtained under the tradename Paranox 56, a product of standard Oil Company of New Jersey. 2 /2% of the Paranox 56 may be added to the oil to obtain 0.75% by weight based on the oil of the metal phenate containing an aryl sulfide substituent. The Standard Diol HD referred to in the above table is an oil sold under that brand name by standard Oil Company of New Jersey and believed to contain a small amount of a compound'of the type formula-- HOMO OMOH inhibitors disclosed herein may be utilized in com-' bination to give a superior lubricant. Salts of this type are exemplified by the following type formulae:

325 F., strip corr. test- The calcium polyaxnyl naphthoyl benzoate re ferred to in' the above table is a compound of the type fcrmula-- The Socony-Vacuurn RDS-203 is an oil believed to containa small amount of a tin salt of a paraffin wax substituted salicylic acid. In any event, the paraiiin wax thiomer is operative with such salts and in the compounded oils of this name.

Salts of polycarboxylic acids in combination with the corrosion inhibitors disclosed herein may be utilized to yield superior lubricants. Exemplary type formulae of polycarboxylic acids from which these salts may be formed are as follows:

(CnH2n-{-2x) (cool-z).

(can "(000m 2 aoocccnnn coon in which 12 may be zero or a whole number, gen-: erally from 1 to 8 inclusive, :1: is a whole number from 1 to n, and in which there may or may not be alkyl, aryl, aralkyl or carbocyclic substitution to increase oil solubility. Improved salts of this type are obtained when n. is greater than 1 and the acid contains a polar group substitution in a position alpha, beta, gamma, delta-or epsilon to the carbon atom of the salt-forming carboxylic acid group. The term polar group as used herein includes the following:

and the like.

The efiectiveness of this combination is illustrated by the following data:

325 F., strip 0011'. test, 01 mg. wt. loss 24 hrs. 48 hrs. 72 hrs.

Kettleman (Calif) s. A. E. 30 vr=se 0.5% calcium cetyl citrate Kettleman ((lalif.) S.A.E. 30 (VI=86)+ 0.5% calcium cetyl citrate+l% parafiiu wax thiomer 0.8

Calcium, barium, strontium, magnesium, zinc, cadmium, aluminum, tin, chromium, iron, cobalt and nickel salts of the polycarboxylic acids, preferably partially esterifled, may be utilized. Ex- .amples of acids from which such salts may be prepared by known methods are: oxalic acid, malonic acid, isosuccinic acid, gluteric acid, adlpic acid, pimelic acid, suberic acid, sebacic acid, fumaric acid, maleic acid, malic acid, tartronic acid, tartaric acid, citric acid, aminosuccinic acid and the like. It is preferred that each of the above acids be partially esterified and that the metal salts be a salt of a partially esterified acid.

Examples of salts of alkyl carboxylic acids containing a polar group near a carboxyl group of the acid are: the calcium, barium, strontium, magnesium, zinc, tin, aluminum, chromium, iron, cobalt and nickel salts of alpha, beta or gamma hydroxy iaiu'ic, myristic, palmitic, stearic and arachidic acids; the calcium, barium, strontium, magnesium, zinc, tin, aluminum, chromium, iron, cobalt and nickel salts of alpha, beta or gamma this, mercapto, merca'ptide or. thiono substituted lauric, myristic, palmitic, stearic and arachidic acids and the calcium, barium, strontium, magnesium, zinc, tin, aluminum, chromium, iron, co bait and nickel salts of alpha, beta or gamma amino substituted lauric, myristic, palmitic, stearic and arachidic acids. The effectiveness of these salts in lubricating oils may be enhanced by use in combination with the multi-bridged thioalkyl compounds herein disclosed.

Examples of metal alcoholates which may be added to hydrocarbon oils together with the multi-bridged thioalkyl inhibitors comprise the alkali, alkaline earth, aluminum, and heavy metal alcoholates, e. g. sodium, potassium, calcium, barium, strontium, magnesium, zinc, cadmium, tin, aluminum, chromium, iron, cobalt and .nickel alcoholates. Examples of alcohols utilized to form the metal alcoholates are the higher alcohols, such as amyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl, oeryl, myricyl and unsaturated alcohols, such as are derived from lanolin.

For the purposes of clarity and emphasis it is again pointed out that each of the multi-bridged thioalkyl compounds, and particularly the paraffin wax thiomers hereinbefore disclosed, maybe utilized either as a corrosion inhibitor or as a sensitizer for hydrocarbon oils to be stabilized with any of the aryl metal oxides, salts of aryl carboxylic acids, salts of polycarboxylic acids, salts of alkyl carboxylic acids containing a polar group, and the metal alcoholates above disclosed. In ome instances, as for example in over-refined or high viscosity index oils having a viscosity index greater than 75, the principal function of the thiomers may be that of a sensitizer rather than a corrosion inhibitor. In other instances, as when the hydrocarbon oil being stabilized is only moderately refined or has a viscosity index less than 75 and the service to be encountered by the compounded oil is severe or with corrosion-sensitive bearings, the principal function of the thiomers may be that of a corrosion inhibitor. In still other situations the thiomers may serve as multi-functional agents to both inhibit corrosion and sensitize the base oil to stabilization with the salt-type inhibitor.

The proportion of the salt-like inhibitors, that is, of the aryl metal oxides, salts of aryl carboxylic acids, salts of polycarboxylic acids, salts of alkyl carboxylic acids containing a polar group, and the metal alcoholates above disclosed, may vary from about 0.1% to 2% by weight in the finished oil. From approximately .5% to 1.5% is usually preferred.

Another aspect of this invention comprises the provision of an activator for the multi-bridged thioalkyl compounds disclosed herein. These activators enhance the eflectiveness of the thiomers herein disclosed in a manner which has not been explained and is not understood.

The activators preferably comprise either an acid ester, that is, a partially esterified acid of a strong acid-forming element such as phosphorus, or of a weak acid-forming element such as arsenic, antimony or boron, or a salt of acids of these strong or weak acid elements containing an organic substituent. .Either the acid ester alone, or the salt alone, or mixtures of salts and acid esters of any of the foregoing may be used as an activator. These types of'activators, when utilized in combination with the foregoing multi-bridged thioalkyl compounds, enhance the corrosion inhibiting or sensitizing action thereof. This is true even though the activator may not, when added alone, be a sensitizing agent for the oil being stabilized.

Illustrative activators which may be added to hydrocarbon oils, such as mineral lubricating oil, according to this invention comprise metal salts in which the metals are selected from groups II, III, IV and VI of Mendelyeevs Table of the Elements. Specific examples of such metals are: calcium, barium, strontium, magnesium, zinc, tin, cadmium, aluminum, chromium, iron, cobalt and nickel. Likewise, the alkali metaland ammonium salts are not precluded.

The salts of substituted acids of phosphorus utilized as activators and illustrating the derivatives of strong acid-forming elements are preferably formed from substituted oxyaclds of pentavalent phosphorus of the following type formula:

where R may be alkyl, aryl, alkaryl, aralkyl or cyclic nonbenzenoid radicals. Substituted phosphoric acids containing at least twelve carbon atoms are preferred, but where the salts are sufficiently soluble in oil, acids containing fewer carbon atoms may be utilized. Examples of preferred type acids are alkyl are alkaryl substituted phosphoric acids having .at least twelve carbon atoms in the molecule. It is to be understood that the broader aspects of the invention includesalts of other types of acids of phosphorus containing more than twelve carbon atoms. Additional examples of such substituted oxyacids of phosphorus are as .follows:

Phosphonic acid Monoestcr of phosphonic acid Rf o Phnsphinic acid where R and R1 may be alkyl, aryl, alkaryl, aralkyl or cyclic nonbenzenoid groups which, in turn, may be pure hydrocarbon constituents or oxygenated hydrocarbons such as alcohols, ketones, esters and ethers, or hydrocarbons containing substituents such as halogens (chlorine, bromine, iodine), amino, or nitro groups. Likewise, R and R1 may be an oil-soluble heterocyclic constituent; for example, a radical containing a nitrogen ring.

In general, salts of substituted derivatives of acids of phosphorus, such as phosphorous acid, HsPOs; hypophosphoric acid, H2PO3; orthophosphoric acid, H3PO4, pyrophosphoric acid, H4P201, and the sulfur analogues of these acids fall with in the broadest aspects of the invention. By acids of phosphorus containing an organic substituent or by substituted acids oi phosphorus wherever used herein it is intended to designate acids of phosphorus containing an organic group of the types previously listed. The organic groups may be either directly attached to the phosphorus atom of the compound or attached thereto through an intervening atom, such as oxygen or sulfur. The term oxyacids of phosphorus" is used to designate throughout the specification and claims acids of phosphorus in which only an oxygen atom may intervene between the hydrogen and phosphorus atoms of the parent acid.

Additional examples of activators comprising derivatives of weak acid-forming elements are metal salts oracld esters derived from acids se-- lected from the following groups:

TYPE 1.-Acms OF Bonow CONTAINING AN On GANIC SUBSTITUERT Organic bomnic Mids B OH r nic burials? maids R-O-B Monoesters of orthobodo mid B0H R'-0 Diet-Item of Orthoborio acid 8 H 3-H OH Organic monothIo-boronlc acids Organic dlthlo'bm'onic acids Organic thio-boroniclclds OH RBB Monoeaters of monothi -m'am bflflo lcld Monomers oi organza monothio-bodc acid BOB H I Monoasters of ammo dithIo-boflc sci d Diesters of monothio-orgsno boric acid B- S H Diesters o! thIo-organo thio-boric acid 0 ortho-araonoua acid (mine dlhydwxides) 0mm minous acid (diorama substituted mine hydroxide) O R R- As Monoesfar of organ: ottho-arsonous acid RAs Orzann monothlo-emnous acid B-As Organs dlthlo-monnna acid Monneate: o! orzmo monothIo-arsonom acid RA.s

Monoesva: o1 Orgnno dlthlo-amonoua acid Monoastm' o1 araanous acid Diesber a! arsenms acid Monothic-ester of amnuus acid 5 R A9 R ll OE lii'onothio-dlcster oi arsenic acid S R A 8 R ("i OH Dithio-diester of arsenic acid S R A5 0 R I S H Monothio-diester of monothiol-arsenic acid 0 R As OH g OH Monoester of monothion-ezsenic acid 0 a A840 R g OH Dlester of monothion-arsenic acid S R As Ofl S OH Monothio-ester oi monothion-arsenic acid 8 R A5 5 H g OH Monothioester of thion-monotbiol-arsenic acid 8 R A8 8 H 8 S H Monothio'ester of tetrathioarsenlc acid S R A5 0 R i OH Monothio-diester oi thion-arsenic acid 5 B. As 8 R g on Dithioxliester 0i thion-arsenic acid S R A5 0 R g S H Monothio-diester of thion-monothiol-arsenic acid like derivatives thereof with which the present invention is concerned. Accordingly, existence of the free acid in a stable form is not a prerequisite to the preparation of the derivatives thereof contemplated herein. It should also be observed that various of the salt-like derivatives are relatively insoluble in organic solvents such as hydrocarbon 011s. However, oil-solubility is not an absolute prerequisite for utility or the present invention in its broadest aspects, as will be explained in more detail hereinafter; nevertheless, oil-soluble compounds are preferred. Some of the salt-like compounds and esters are unstable at high temperatures. 'When the compounded oil is to encounter high temperature conditions during use compounds known or found to be more stable at elevated temperatures should be selected.

Activating agents contemplated within the broader aspects of the invention are in general salts, and preferably polyvalent metal salts, of the following acid reacting compounds: organic substituted derivatives of acids of boron, such as orthoboric, H3303; mesoboric, H4B2O5; metaboric, H2B2O4; dihydrodiboric, 114E208; hexahydrotetraboric, HGBdOB (once called pyroboric acid); dihydrotetraboric, H2B407; hexahydrohexaboric, HcBeOia; dihydrohexaboric, HzBeOio; hexahydro-octoboric, HGBBOIB; dihydro-octoboric, HzBeOia; dihydrodecaboric, HzBioOie; dihydrododecaboric, HzBizOis; organic substituted derivatives of acids of arsenic, such as alkyl arsine hydroxides or oxides, alkyl arsine sulfides, dialkyl arsine hydroxides or oxides, dialkyl arsine sulfides, aryl arsine hydroxides or oxides, alkaryl arsine hydroxides or oxides, aryl or alkaryl arsine sulfides and sesquisulfides, diaryl arsine hydroxides or oxides, dialkaryl arsine hydroxides or oxides, diaryl or dialkaryl arsine sulfides, alkyl arsom'c acids, alkyl arsine disulfides, alkyl arsinic acids, aryl arsonic acids, aryl di-arsonic acids, halogenated aryl arsonic acids, nitroaryl arsonic acids, amino aryl arsonic acids, hydroxy aryl arsonio acids, carboxy aryl arsonic acids, alkaryl arsonic acids, alkaryl diarsonic acids, halogenated alkaryl arsonic acids, aryl arsinic acids, alkaryl arsinic acids, aryl trithio-arsonic acids, alkaryl trithio-arsonic acids, aryl arsine disulfides, and alkaryl arsine disulfides.

The proportion of activating agents herein disclosed which may be added according to the principles of the present invention may vary depending upon the uses involved and the properties desired. As little as 0.05% by weight of various of the compounds gives measurable improvements. From approximately 0.1% to 2% of the compounds may be added to liquid lubricants. In general, from approximately 0.25% to 0.75% has been found preferable, particularly when used in conjunction with from approximately 0.25% to 1% of an aryl metal oxide and 0.5% to 1.5% of the paraflin wax thiomers.

A preferred embodiment of this invention provides a mineral oil composition containing three types of components, namely:

(1) A metal salt of an organic acid in an amount (2) A corrosion inhibitor and/or a sensitizer in an amount sufllcient substantially to reduce corrosion and/or enhance the responsiveness of the hydrocarbon oil to the stabilizing action of .the metal salt stabilizer. When the base oil being stabilized is of high viscosity index or over-refined, this second ingredient usually functions primarily as a sensitizer. When the base oil is of low viscosity index or low refinement, the ingredient may serve primarily as a corrosion inhibitor. In moderately refined or moderate viscosity index base oils, this type of ingredient serves both as a sensitizer and a corrosion inhibitor. The corrosion inhibitor and/or sensitizer is a long carbon chain multi-bridged thioalkyl compound of the type previously disclosed herein. The many examples given in this specification may be utilized in the present preferred embodiment of the invention but, as previously indicated, the paraffin wax thiomers are outstanding.

(3) An activator for the sensitizer and/or corrosion inhibitor for increasing the effectiveness thereof. The activators comprise either an acid ester, that is, a partially esterified acid of phosphorus, arsenic, antimony or boron, or a salt of acids of these elements containing an organic substituent, as disclosed hereinbefore.

The following data on oilscompo unded with the above three types of ingredients are illustrative:

The strip corrosion tests in Tables I and II were carried out in the same manner as described previously for 325 F. and 300 F. corrosion tests,

respectively.

In the compounded oils containing the combination of three additives as above described, the proportions may be as previously indicated, namely, from about 0.1% to 2% by weight, and preferably from approximately 0.5% to 1.5% by weight based on the oil, of the salts of organic acids; from about 0.1% to about 2% by weight based on the oil of a corrosion inhibitor and/or sensitizer, and preferably from about 0.25% to 1.5% thereof; and from as little as 0.05% to 2% by weight based on the oil of the activator, from approximately 0.25% to 0.75% being preferable.

The compounded hydrocarbon oils herein disclosed may have one or more advantages depending upon the particular compounding agent or combination of compounding agents selected, the proportions utilized, and the environment which the lubricating oil is to encounter. It should be observed, for example, that even though a compounded oil may be somewhat corrosive to one particular type of bearing alloy, other bearings may be little if at all aflected by such corrosive action. Hence, compounding agents or combinations thereof which may not be particularly desirable for lubrication of a special type of bearing, where corrosion becomes a factor of importance, may nevertheless be highly useful and extremely advantageous in conjunction with the operation of internal combustion engines having corrosive-resistant bearing-metals. Like- TABLE I 325 F. strip corrosion test on S. A. E. 30 oil from Kettleman crude (California) 0.5 sulfurieed calcium cetyl phenate 0.25% calcium cetz/Z phosphate 0.25% thiomer Multi-bridged thiomer compounding agent Pb uwt. loss mmg. Per- Per- Percent Percent fi' fi i g: Y gd z cent cent 01 in by wt. Preparation by so u 5 C1 orig. wax in oil 2411211. 48 hrs. 72 hrs.

0 11.0 30.5 44:0 7 e 1 as 45 1,753 680 12. 2 11. 5 2s 0. 25 Reaction of chlorinated parai- 0.7 1.1 3 031 9% 13 3 m 3 26 0 25 flniwsx with sodium sulfide. +0 3 1 o 0.0 1, 012 504 7. 5 3. 7 l5. 4 0. 25 Reaction oi cl1lorinated lubri- 3. 6 11.0 11.; g 1% I eating oil with sodium e s e 0 25 Rsulgide' 1 i 590 873 2.2 l one on wax p0 ymerca tde 6.3 16.7 with chlorinated wax. p 19 1 1 15 10 TABLE I! 300 F. strip corrosion test (coarse grained bearings) on S. A. E. 10 oil from Colombia grade 0.5% sullurized calcium cetyl phenate 0.25% calcium cetyl phosphate 1% thiomer I Multi-bridged thiomer compounding agent Cu-Pb wt. loss mmg.

. Viscosity Neut. Naphtho Per- Per- Percent Percent increase v at 1 1 a N0. 111801111316 cent cent 01 in by wt. Preparation b 24 hr 48 i1 at 210 s Cl orig. wax in oil y 8 rs 72 m 0 0. 4 112. 4 259. 4 3 4 4. 18 71 1 753 680 12. 2 11. 5 2o 1 Reaction of chlorinated paraf- 0.4 .3 i 1 .0 1. 1 .2 .6 R i resists?- 9 29 6 u 1,55 5' eec ion 0 c or a e para- 3.7 17.8 34. fin wax with sodium sulfide 4 1 32 27 i 2 6 1 7 1G 1 R t i i i' i t d r 1, 224 1,525 1 one 1011 o c or us e para 0.2 6.7 1 6 500 8 O 1 O 16 I R t l'iflllllsogiumgulflde 12 6 L9 1- 18 2,38 1, 1 eac ion 0 c or nate paraf- 3.1 3.2 fin wax with sodium sulfide +3 7 6 17 4 5 3 7 15 4 R l 1 l i t dl b i 1,012 1 eac ion 0 c or as e u r 3.7 22.1 1 gaiting oil with sodium sul- 66 9 25 y e.

590 8"3 6.8 2.2 16 2 Reaction wax polymerca tide 2.0 l g I with chlorinated Wax. p 5 6 29 6 6 24 wise, combinations or compounding agents which are not sufliciently. Powerful to stabilize a particulanoilstock under the most extreme. conditionsxmay, nonetheless, be highly advantageous msuch oils where the environment to be encountered isnot so severe. Thepresent invention in its broader aspects is therefore not limited to the particular compounding agent or combination of ingredients giving the greatest stability or passing all of the very severe tests which have been devised. The invention embraces various of the less advantageous additives or comticular-applications where all possible improve ments in properties oi the oii may'not be v.requiredor' where the standard oiv'periormance 'binations thereof which may'fin'd utility in par- The compounding agents and combinations of invention appear at present to find their greatest utilityin over-refined or highly parafiinic mineral lubricating oil stocks,which stocks have heretofore been the most difiicult to stabilize.

However, it isto be understood that the invention is not limitedqto such base stocks since advantages herein disclosed 'may be obtained with moderately refined or less 'paraifinic lubricating oilsjor even lowv iscosity index lubricants.

The compounding agents ofthis invention" may also be added to hydrocarbon oils containing .additional'ingredients, such as pour point de- "pressants oiliness agents, extreme pressure addition agents, blooming agents, compounds for enhancing the viscosity index. of the hydrocarbon oil, thickening agents and/or metal soapsfiny grease-forming. proportions v or in amounts in- .sufilcient toior'm grease, as in the case of mineral castor" machineoiIs orothencompounded liquid v lubricants.

In the ioregoingdisclosure an upper limit of approximately 2% by weight based on the oil of eachof-thecompounding-agents has been indi cated as sufiicient for a finished oil. The present invention also embraces solutions containing more than 2% oi the novel combination of compounding agents. Concentrates containing high percentages of the additives or this invention comprise a convenient method of handling the compounding agents, and the concentrated solutions may be sold and used as addition agents for lubricants in general. Thus mineral oil solutions containing as much as 50% or more by weight of the compounding agents may be prepared. Such concentrated solutions are adapted for dilution with hydrocarbon lubricating oil to yield a finished product containing, for example, from approximately 0.5% to 1.5% by weight .of a metal phenate; from approximately 0.25% to 1.5% by weight of' a paramn wax thiomer; and from approximately 0.25% to 0.75% by weight based on the oil of a metal salt of an acid of phosphorus containing an organic substituent. Concentrated solutions of the additives in organic solvents capable oi dilution with mineral lubricating oil to form a homogeneous mixture containing the above proportions of compounding agents comprise a part of this invention.

While the character of the invention has been described in detail and numerous examples or action thereof,

of illustration only and withthe intention that no limitation should be imposed upon the inventio'n thereby. It will 'be apparent to those skilled in the art that numerous modifications and variations of the illustrative examples may be, effected in the practice of the invention which is ofthe scope'oi the claims appended hereto.

1.. A lubricating oil having a corrosion index greater than about 40 containing a parafiin wax thiomer in an amount sufficient to inhibit the corrosive action oi said lubricating oil. I

2. A lubricating oil having-a corrosion index greaterthanabout 4qcon'taining a paraflin wax" poly-(monothimdimer in an amount s'umcient to inhibit the corrosive action of said lubricating oil.

. 3. A lubricatingoil corrosion ind'e'x 'greater'thanabout 40 containing a parafiln wax di-(monothio) dimer in an amount suiilcient to inhibit, the :corrosive action of said lubricating oil. U e

1. 4. A viscous hydrocarbon. oilsubject to deterioration at elevated temperature, anaryl metal oxide in an amount sufiicient substantially to I inhibit said deterioration, and an inhibitor capable of reducingcatalysls ,of corrosion by said aryl -metal oxide without destroying thelstabilizing said. inhibitor. comprising a parafiin wa'x thiomer.

A viscous hydrocarbon oil subject deterioration at elevated temperature, a metal salt of an aryl'carboiwlic acid in anamount sufiicient substantiallyto inhibit said deterioration. and 'an inhibltorcapable of reducing catalysis of corrosion 'byk said salt of an aryl carboxylic acid without destroying, the stabilizing action thereof, said inhibitorcomprising a parafiin wax thiomer.

6.}; viscous hydrocarbon oil subject to deterioration at elevated temperature, a metal salt of a partially esterified polycarboxylic acid in an amount sumcient substantially to inhibit said deterioration, ,and an inhibitor capable of reducing catalysis of corrosion by said salt of a partially esterified polycarboxylic acid without destroying thestabilizing action thereof,-said inthe compounds given, this has been done by way hibitori comprising a parafiln wax thiomer.

7. 'A viscous hydrocarbon oil subject to de terioration at elevated temperature, a metal alcoholate in an amount'sufiicient substantially to inhibit said deterioration, and an inhibitor capable of reducing catalysis of corrosion by said metal alcoholate without destroying the stabilizing action thereof, said inhibitor comprising a parafiin wax thiomer. I

8. A lubricant comprising a-viscous hydrocar- .bon oil subject to deterioration at elevated temperature, a metal salt oI-an organic acid in'an amount sufilcient substantially to inhibit said deterioration. a parafiln-wax thiomer sensitizerfor the hydrocarbon-oil capable of enhancing its responsiveness to the stabilizing action of said metal salt, and an activator capable of enhancing theefiectiveness of said thiomer sensitizer, said activator comprising a salt of an acid of phosphorus containing an organic substituent.

9. A lubricant comprising a viscous hydrocarbon oil subject to deterioration at elevated tem perature. an aryl metal oxidein an amount sufficient substantially to inhibit said deterioration, a parafiin wax thiomer sensitizer for the hydrocar bon oil capable of enhancing its responsiveness to the stabilizing action of said aryl metal oxide,

and an activator capable of enhancing the efl'ectiveness of said thiomer sensitizer, said activator comprising a salt of an acid of phosphorus containing an organic substituent.

10. A lubricant comprising a viscous'hydrocarbon oil subjectto deterioration at elevated temperature, a metal salt of an aryl carboxylic acid in an amount sufllclent substantially to inhibit said deterioration, a paraflln wax thiomer sensitizer for thehydrocarbon oil capable of enhancing its responsiveness to the stabilizing'action of said salt of an aryl carboxylic acid, and an activator capable of enhancing the efiectiveness of said thiomer sensitlzer; said activator comprising a salt of an acid of phosphorus containing an organic substituent.

11. A lubricant comprising a viscous hydrocar- I bon oil subject to deterioration at elevated temperature, a metal salt of a partially esterifled polycarboxylic acid in an amount sufllcient substantially to inhibit said deterioration, a parafiln wax thlomer 'sensitizer for the hydrocarbon oil capable to thestabilizing of enhancing its responsiveness action of said salt of a partially esterified' polycarboxylic acid, and an activator capable of enhancing the effectiveness of said thiomer sensi+ tizer, said activatorcomprisinga salt of an acid of phosphorus containing an organic substituent. v 1 i 12. A lubricant comprising a viscous hydrocarbon oil subject to deterioration at elevated temperature, a metal alcoholate in an amount willcient substantially to inhibit said deterioration, a para-filn wax thiomer sensitizer for the'hydroe carbon oil capable of enhancing its responsiveness to the stabilizing action of said metal alcoholate,

2 i o o by weight based 15, A lubricant comprising a hydrocarbon lubricating oil, from approxima fily, 0ll% to 2% by weight based on the oil of an aryl metal oxide of a polyvalent metal, from approximately 0.1% to approximately 2% by weight based on the oil of a paramn wax thiomer, and from approxiomately 0.05% to 2% by weight 7 based on the oil of a polyva'lent metal salt of an acid of phosphorus containing an organic substituent.

16. A lubricant comprising a hydrocarbon lubrieating oil, from approximately 0.1% to 2% by weight based on the oil of apolyvalent metal ,salt of an aryl carboxylic acid, from approximately 0.1%- to approximately 2% by weight based on the oil of a paraflin wax thiomer, and from approximately0.05% to 2% by weight based on the oil otapolyvalent metal salt of an acid of phosphorus containing an organic substituent. 1'7. A lubricant comprising a hydrocarbon lubricating oil, from approximately 01% to 2% by weight based onthe oil of a polyvalent metal salt of a partially esterifled polycarboxylic acid, from approximately, 0.1% to approximately 2% by weight basedion the oil of aparafiin wax thiomer; and from approximately 0.05% to 2% salt of an acid of phosphorus containing an or& g

ganic substituent.

' I 18. A viscoushydrocarbon oil having a corro-v sion index greater than about containing a thiomer having a long'ch'ain con paraflin wax taining at least 20 carbon atoms, said paraflln wax and an activator capable of enhancing the eflectiveness of said thiomer sensitizer, said activator acid of phosphorus concomprising a salt oi! an taining an organic substituent.

13. A lubricant comprising a viscous hydrocarbon oil, an inhibitor comprising a paraffin wax thiomer, and an activator for enhancing the effectiveness of said inhibitor comprising a salt of an organo-substituted acid of an element selected from the group consisting of phosphorus, boron and arsenic.

14. A lubricant comprising a viscous hydrocarbon oil, an inhibitor comprising a paraffin wax thiomer, and an activator for enhancing the efiectiveness or said inhibitor comprising a salt of an acid 0'! phosphorus containing an organic stituent.

sub-

thiomer being present in a small amount sufilcient substantially to reduce the corrosion index of said 'oil andto sensitize said oil to the stabilizing action of an aryl metal oxide.; I v

19. A viscous hydrocarbon oil having a corrosion index greater than about 40 and a parafiin wax thiomer sensitizer for the hydrocarbon oil, said sensitizer "least 20 carbon atoms and being present in a small amount having a long chain containing at sufiicient to enhance the stabilizing action of an aryl metaloxide on said hydrocarbon oil, and an activator capable of enhancing the effectiveness of said parafiin wax thiomer sensitizer, said activator comprising a polyvalent metal salt of an organo-inorganic acid.

BRUCE B. FARRINGTON. VICTOR M. KOSTAINSEK. GEORGE H. DENISON, JR.

on, the oil of a polyvalentmetal v 

